1. Field of the Invention
This present invention relates to transceiver antennas for use in accessing lower earth orbit, stationary geo-syncronous and/or geo-stable satellites, and more particularly to such an antenna employing low cost manufacturing construction for quadrifilar helix antennas.
2. Brief Description of the Prior Art
Conventional communication systems are known in the prior art for providing a communications link between satellites which continuously transmit information and a hand-held transceiver unit such as a mobile telephone or the like. The transceiver may be at a stationary base or may be located in a mobile vehicle. The accuracy of satellite transmission is dependent on the quality of the signal detected from the satellite by the transceiver antenna. Hence, the system requires a sufficiently accurate receiver and antenna arrangement such that the antenna must be small and portable with a hemispherical beam pattern broad enough to detect signals from satellites located anywhere in the hemisphere. For this purpose, the quadrifilar helix antenna has been found to be well suited.
Attempts have been made to produce quadrifilar helix antennas for satellite signal reception such as those disclosed in U.S. Pat. Nos. 5,349,365; 5,198,831; 5,134,422 and 5,485,170. Difficulties and problems have been encountered with these prior art antennas in that the complexity of manufacture has led to substantial costs in fabrication and production and therefore, such antennas are not readily easy to produce. Difficulty in construction resides in the fact that the helix includes continuous filament winding about a standard form or requires bending of filaments or ribbons about a form or even entails costly etching techniques to place the filaments or ribbons onto a form. Thus, prior art quadrifilar helix antennas involving such constructions are impractical for lower antenna costs and such antennas are not necessarily enclosed to protect the current carrying filaments or ribbons such that the antenna design is too delicate for rough handling and adverse environmental conditions.
Therefore, a long-standing need has been in existence to provide a low cost quadrifilar helix antenna for satellite telecommunication applications in which it is desirable to both transmit and receive capabilities in a telecommunication unit such as a cellular phone or the like and wherein the antenna must be able to efficiently transmit radio signals to the satellite and receive return signals as well. In order to provide low cost, it is preferred that the antenna be constructed by means of using injection molding techniques as well as using conventional plating fabrication methods.